perhaps he the mechanic , is an IDIOT or CROOK... when you pump the brake pedal down and hold it when bleeding , you then open the bleed screw and it should be solid fluid. this is solid pure hydraulic pressure. if any air bubbles that is a defect and the air must be removed resulting in the the soft pedal... because brake fluid/hydraulic fluids do not compress ,,,,,,,,,,,,, air does compress .. also air in brake fluid causes the fluid to breakdown because air has water ... the master does not cause a soft pedal ..he is trying to get more $$$ out of you , go to another shop have them bleed the system ... do not tell them any prior work done just tell them to bleed it. see what happens . if it fixes it which I believe it will. then I would tell all to not go to that mechanic .. a woman that requires vehicle repairs often [even dealerships do it ] are abused and ripped off.